Insulin-like growth factor-binding protein-2 is required for osteoclast differentiation.
Insulin-like growth factor-binding protein-2 is required for osteoclast differentiation.
复制标题
DOI：
10.1002/jbmr.545
复制
发表时间：
2012-02
影响因子：
6.2
通讯作者：
Clemmons, David
中科院分区：
文献类型：
--
作者：
DeMambro, Victoria E.;Maile, Laura;Wai, Christine;Kawai, Masanobu;Cascella, Teresa;Rosen, Clifford J.;Clemmons, David
Igfbp 2基因的整体缺失导致骨转换的抑制。为了研究IGFBP-2在调节破骨细胞分化中的作用，我们培养了Igfbp 2 −/−骨髓细胞，发现破骨细胞数量减少，吸收受损。添加全长IGFBP-2恢复破骨细胞分化、融合和再吸收。为了确定IGFBP-2的分子结构域，需要这种效果是明显的，Igfbp 2 −/−骨髓细胞小鼠转染与构建体，其中肝素结合（HBD）或IGF结合结构域的IGFBP-2突变。我们发现，这两个域是破骨细胞生成所必需的，因为任何一个域的突变形式的表达都不能支持功能成熟的破骨细胞的形成。为了辨别IGFBP-2调节破骨细胞形成的机制，分析了PTEN丰度和磷酸化状态以及AKT对IGF-I的反应性。与对照组相比，Igfbp 2 −/−细胞的PTEN和磷酸化PTEN水平升高。野生型IGFBP-2的表达使PTEN的水平降低到野生型细胞的水平。表达IGF结合突变体的细胞表现出与野生型蛋白相当的PTEN和磷酸化-PTEN抑制，而表达IGFBP-2 HBD突变体的细胞没有表现出PTEN抑制。当通过Thr 308和Ser 473磷酸化测量IGF-I刺激AKT活化的能力时，分析了前破骨细胞中响应IGF-I的Ser 473的刺激需要完整的IGFBP-2的存在。通过添加防止PTEN磷酸化的CK 2抑制剂，这种效果得以复制。相反，在完全分化的破骨细胞刺激Thr 308磷酸化需要完整的IGFBP-2的存在。我们的结论是IGFBP-2是破骨细胞生成的重要调节因子，肝素和IGFBP-2的IGF结合域对于完全分化和功能性破骨细胞的形成是必不可少的。
Global deletion of the Igfbp2 gene results in the suppression of bone turnover. To investigate the role of IGFBP-2 in regulating osteoclast differentiation we cultured Igfbp2−/− bone marrow cells and found a reduction in the number of osteoclasts and impaired resorption. Addition of full length IGFBP-2 restored osteoclast differentiation, fusion and resorption. To determine the molecular domains of IGFBP-2 that were required for this effect to be manifest, Igfbp2−/− bone marrow cells mice were transfected with constructs in which the heparin binding (HBD) or the IGF- binding domains of IGFBP-2 were mutated. We found that both domains were necessary for osteoclastogenesis since expression of the mutated forms of either domain failed to support the formation of functionally mature osteoclasts. To discern the mechanism by which IGFBP-2 regulates osteoclast formation, PTEN abundance and phosphorylation status as well as AKT responsiveness to IGF-I were analyzed. Igfbp2−/− cells had elevated levels of PTEN and phospho-PTEN compared with controls. Expression of wild-type IGFBP-2 reduced the level of PTEN to that of wild-type cells. Cells expressing the IGF binding mutant showed suppression of PTEN and phospho-PTEN equivalent to the wild type protein, whereas those expressing the IGFBP-2 HBD mutant showed no PTEN suppression. When the ability of IGF-I to stimulate AKT activation, measured by Thr308 and Ser473 phosphorylation, was analyzed, stimulation of Ser473 in response to IGF-I in pre-osteoclasts required the presence of intact IGFBP-2. This effect was duplicated by the addition of a CK2 inhibitor that prevents the phosphorylation of PTEN. In contrast, in fully differentiated osteoclasts stimulation of Thr308 phosphorylation required the presence of intact IGFBP-2. We conclude that IGFBP-2 is an important regulator of osteoclastogenesis and that both the heparin and the IGF binding domains of IGFBP-2 are essential for the formation of fully differentiated and functional osteoclasts.
登录
查看更多内容
影响因子：
4.8
作者：
Hoeflich, A;Nedbal, S;Wolf, E
通讯作者：
Wolf, E
影响因子：
4.8
作者：
Kawai, Masanobu;Breggia, Anne C.;Rosen, Clifford J.
通讯作者：
Rosen, Clifford J.
影响因子：
64.5
作者：
Padmanabhan S;Mukhopadhyay A;Narasimhan SD;Tesz G;Czech MP;Tissenbaum HA
通讯作者：
Tissenbaum HA
影响因子：
5.3
作者：
Vazquez, F;Ramaswamy, S;Sellers, WR
通讯作者：
Sellers, WR
影响因子：
4.8
作者：
Shen, Xinchun;Xi, Gang;Clemmons, David R.
通讯作者：
Clemmons, David R.